The input-output function of a neuron is defined by the combined expression of synaptic and intrinsic properties. These properties are not static and many forms of plasticity involve coordinated changes in both synaptic strength and intrinsic excitability. However, the way in which a neuron co-regulates these properties is not well-understood. This project aims to define the underlying relationship between a neuron's intrinsic and synaptic properties, focusing on the retino-tectal circuit of the tadpole, where postsynaptic tectal neurons receive direct input from retinal ganglion cells. A series of whole-cell electrophysiological recordings will be carried put in order to characterize the relationship between intrinsic and synaptic properties expressed in individual neurons. Aim 1 characterizes how synaptic and intrinsic properties of the tectal neurons change throughout development of the retino-tectal circuit. Aim 2 explores how specifically altering either an intrinsic or synaptic property during development may alter (1) the input-output function of the neuron, (2) circuit formation. Aim 3 addresses how modulation may regulate intrinsic and synaptic properties and, ultimately, circuit function. Dysregulation of these processes may ultimately lead to pathological states such as epilepsy. [unreadable] [unreadable]